It should be noted that reference to the prior art herein is not to be taken as an acknowledgement that such prior art constitutes common general knowledge in the art.
Suspended ceilings, which may also be referred to as drop ceilings or false ceilings, are well known and are available in a variety of design options. Suspended ceilings typically include a suspended grid of support members hanging from wires or rods attached to the plenum, and panels or planks secured to the grid. The popularity of these ceilings is due, at least in part, to the visual and acoustic benefits coupled with the simplicity and ease of installation of the system.
The most common form of suspended ceilings includes light weight panels, often square or rectangular in shape, that “drop” into a supporting T-grid without additional fastening mechanisms. These types of drop ceilings provide easy access to the plenum space above the ceiling for access to air conditioning equipment, wiring, plumbing, and the like. However, many customers, both residential and commercial, view these types of ceilings as unattractive.
Accordingly, there has been an increasing demand for more aesthetically pleasing suspended ceilings that include a flush building board ceiling finish. These systems typically remove the supporting T-grid and direct-fix plasterboard to a grid-work of channels and overhead structure to provide a more pleasing flush finish. These systems use clips and hangers in order to suspend a grid of furring channel and top cross rails below a supporting structure which can then be sheeted with an appropriate board lining. This allows the designer to bring the ceiling level down to the required height and provides space in the ceiling cavity for services such as air-conditioning.
These direct-fix systems may be more aesthetically pleasing, but present installation difficulties not associated with the more common drop-in panels. These types of system typically require special supporting grids in order to suspend the plasterboard. The specialised supporting grids contain a grid work of channels which may render the ceiling system more expensive and/or more complicated. With plasterboard being directly fixed to a furring channel the distance between the finished plasterboard surface and the top cross rail is determined by the locking key which retains the furring channel to the top cross rail. This minimum distance needs to be considered when mounting items in or on the ceiling system. For example, the small clearance between the top cross rail and the furring channel can be problematic when mounting recessed lighting or the like components in the ceiling.
Given the number of furring channels and top cross rails required to direct fix the plasterboard, it can be somewhat limiting where items like lighting, speakers and air conditioning ducts and vents can be placed. These items are typically flush mounted onto the outside surface of the plasterboard and the majority of the size of these items is located within the ceiling cavity formed between the plasterboard and the grid work of channels forming the suspended ceiling frame. Therefore there needs to be sufficient clearance within the cavity for these items. Likewise these items are normally mounted using some form of clip retainer which needs to be located on the opposite side of the plasterboard to where the item is located, so there must also be sufficient clearance for these attachment devices within the grid work of channels of the suspended ceiling.
A number of difficulties also exist in that they are time-consuming to install and accuracy of spacing may be poorly maintained over large expanses of ceiling. Support system designs that provide ready access into the plenum above usually do so at the expense of a cluttered appearance with too much of the support system being visible from below. Another problem is that supports that pass alongside recessed fluorescent lighting fixtures often intrude into the area that should be kept clear in order to realise minimum interference with the flow of room supply air furnished by air supply boots attached to the fixtures.
Clearly it would be advantageous if a locking key for a suspended ceiling could be devised that helped to at least ameliorate some of the shortcomings described above. In particular, it would be beneficial if a locking key which has the ability to provide a clearance between the top cross channel and the furring channel was devised or to at least provide a useful alternative.